在PHP while循环期间页面不会加载和服务器崩溃

Question

I am trying to run a php script that says basically, whilst two cells in my MySQL database are empty (t_trailerarrival and t_endsort), do something.

My code is as follows:

<?php
// Start Session, include authentication and dBConnection script
session_start();
include 'dbcon.php';
include 'sql_actuals.php';
$current_time = date("G"); 

while($query9_row['a_trailerarrival'] == NULL && $query10_row['a_endsort'] == NULL) {
    echo "Trailer Arrival";
}

The $queryx_row['abc'] are all in the sql_actuals script that is included into this script.

For some reason, every time i run this script - my browser wont load the result (just loads for ever) and then my website at windows azure seems to crash and take a few minutes to restart.

Could someone please advise if there is a massively obvious error with my script? or point me at what the possible issue could be.

Many thanks in advance.

FYI, i have tried adding a line sleep(1); so that it gave the server it runs off a delay before having to run the program again but no luck.

Answer 1

You are not actually doing anything in your while statement except echoing a line.

Therefore

$query9_row['a_trailerarrival'] == NULL 

and

$query10_row['a_endsort'] == NULL

are always true and never changing, and it will never exit the while loop. You need to put exit criteria in the while loop, such as:

$i=0;
while(($query9_row['a_trailerarrival'] == NULL 
        && $query10_row['a_endsort'] == NULL ) 
       || $i==10) {
    $i++;
    echo "Trailer Arrival";
}

Although, logically speaking, you still need to run the query data.

** Edit ** Based upon your feedback, this doesn't sound like a while loop at all, but rather an if statement you need (with multiple elseif s).

if ($query9_row['a_trailerarrival'] == NULL && $query10_row['a_endsort'] == NULL){
   echo "Trailer Arrival";
} elseif ($query9_row['a_trailerarrival'] == NULL  && $query10_row['a_endsort']){
   echo "End Sort";
} elseif ($query9_row['a_trailerarrival']  && $query10_row['a_endsort']){
   echo "First Van";
}else {
  // fourth condition:
  // $query9_row['a_trailerarrival'] != NULL &&  $query10_row['a_endsort'] == NULL
}

I included a fourth condition when $query9_row isn't null, and $query10_row is null.